Energy storage system



FIG. 1 is a front perspective view of an energy storage system, showing our new design;

FIG. 2 is a front plan view thereof;

FIG. 3 is a rear plan view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a side plan view thereof;

FIG. 6 is a side plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines are included for the purpose of illustrating environmental structure and form no part of the claimed design. 

We claim the ornamental design for an energy storage system, as shown and described. 